What level should I be for the Fort Runick mission? Finding it hard.

Are you doing the Mission with the Henchmen that are available from the Outpost?

It should be possible as N/R with a full party. Make sure you are not spreading your attribute points across too many different attributes. Focus on certain skills even if you don't have many of them on your Skill Bar.

Use the Wiki to help with Mission info: https://wiki.guildwars.com/wiki/Fort_Ranik

If you don't have a Guild yet it is a good way to find players and ask for help in-game, you can check our Recruitment section: Recruitment

Just to be sure, are you filling your team with henchmen? The game is designed to be played with full teams. Also, have you redeemed any bonus items you might have access to by typing /bonus into the chat panel?

Level 7, while probably a level or two behind, should not be problematic. Your build (and your competence with it) is always the number one factor in determining success. It'll probably be helpful to get Distracting Shot from the Charr Reinforcements quest. I'd also point out that boss spawns in Prophecies are generally random, so if there's one particular boss that's troublesome you might find a different one next time. Also worth knowing that Healing Signet has been buffed significantly since release, so if it's the warrior boss you're talking about I wouldn't use it as an indicator that you're doing anything significantly wrong.

At this point in the game death magic will serve you well. Don't be afraid to acquire a +1 head gear and rune from ascalon city. If you are using death magic a lot you will want a minimum of 3 soul reaping to help with the energy cost.